When Islam is against idol worship why do the Muslims worship, and bow down

When Islam is against idol worship why do the Muslims worship, and bow down
to the Kaaba in their prayer?

Kaaba is the Qibla i.e. the direction Muslims face during their prayers. It is
important to note that though Muslims face the Kaaba during prayers, they do
not worship the Kaaba. Muslims worship and bow to none but Allah.
It is mentioned in Surah Baqarah:
“We see the turning of thy face (for guidance) to the heavens: now shall
We turn thee to a Qiblah that shall please thee. Turn then thy face in the
direction of the Sacred Mosque: wherever ye are, turn your faces in that
direction.” [Al-Qur’an 2:144]
1. Islam believes in fostering unity
For instance, if Muslims want to offer Salaah (Prayer), it is possible that some
may wish to face north, while some may wish to face south. In order to unite
Muslims in their worship of the One True God, Muslims, wherever they may be,
are asked to face in only one direction i.e. towards the Kaaba. If some Muslims
live towards the west of the Kaaba they face the east. Similarly if they live
towards the east of the Kaaba they face the west.
2. Kaaba is at the Centre of the World Map
The Muslims were the first people to draw the map of the world. They drew the
map with the south facing upwards and north downwards. The Kaaba was at
the centre. Later, western cartographers drew the map upside down with the
north facing upwards and south downwards. Yet, Alhamdullilah the Kaaba is at
the centre of the world map.